This invention relates to an apparatus and method for binding media sheets. More particularly, the invention relates to an apparatus and method for producing a bound document from a plurality of media sheets by individually binding each media sheet to previously bound media sheets.
Current devices and methods for printing and binding media sheets involve printing the desired document on a plurality of media sheets, assembling the media sheets into a stack, and separately stapling, clamping, gluing and/or sewing the stack. In addition to imaging material used to print the document, each of these binding methods require separate binding materials, increasing the cost and complexity of binding. Techniques for binding media sheets using a common printing and binding material are known in the art. These techniques generally involve applying imaging material such as toner to defined binding regions on multiple sheets, assembling the media sheets into a stack, and reactivating the imaging material, causing the media sheets to adhere to one another. These known devices and methods, however, can consume significantly more time than producing an unbound document. Each involves printing the entire or a substantial portion of the desired document, then assembling and aligning the media sheets into a stack in preparation to be bound. Binding the stack of media sheets also entails applying sufficient heat to the binding region to reactivate the imaging material throughout multiple sheets or throughout the entire stack. Consequently, the thickness of the bound document is limited by the device""s ability to adequately heat the binding regions throughout multiple sheets or the stack without damaging the media sheets.
U.S. patent application Ser. No. 09/482,124 filed Jan. 11, 2000 (the ""124 application), incorporated herein by reference in its entirety, describes new techniques for binding documents by individually binding each media sheet to previously bound media sheets using imaging material as the binding material. In one technique for page by page binding described in the ""124 application, heat and pressure are applied to each sheet as it is added to the stack to reactivate the toner or other imaging material used as the binding agent. The rate at which sheets can be successively bound to the stack depends in part on how fast the imaging material can be melted and then cured in the binding process. It is desirable, therefore, when using this type of page by page binding technique to cycle between heating/melting the imaging material and cooling/curing the imaging material and to complete the cycle as fast as possible.
Accordingly, the present invention is directed to a method and apparatus for binding together a plurality of media sheets by successively heating and then actively cooling the imaging material binding agent on each sheet as the sheet is added to the stack. In one embodiment of the invention, a method for binding together a plurality of media sheets includes: applying imaging material to a binding region on a single media sheet and activating the imaging material; collecting the sheet together with previously collected sheets in a stack; heating the imaging material applied to the binding region of the sheet; cooling the imaging material applied to the binding region of the sheet; and repeating the acts of applying, collecting, heating and cooling for each sheet in the plurality of sheets. In another embodiment, an apparatus for binding media sheets having a region of imaging material applied thereto for binding includes a tray for collecting a plurality of media sheets and heating and cooling elements. The heating and cooling elements are movable, for each sheet output to the tray, between a first position in which a sheet in the tray is heated and a second position in which the sheet is cooled.